We have all seen the video. Polar bears wandering the ice fields of Canada, Greenland, Norway or Russia in search of a dwindling supply of food. The image is scientists and environmentalists most dramatic way of conveying the warning that melting sea ice is reducing this animal’s food source. But more fundamentally, it’s an easy-to-understand picture showing that global warming is here and already changing our world.

But we don’t have to go as far as the Arctic Circle to figure this out, says Dr. Pieter Tans, a climate scientist at Boulder’s National Oceanic and Atmospheric Administration. “We have an early spring in the Northern Hemisphere, several weeks earlier than what used to be the norm,” says Tans, pointing out just one example of how he sees the world changing. “It has an effect on species, the timing of when the leaves come out.” It impacts the entire food chain, he says, from mating cycles to hunting.

Tans is one of an overwhelming number of scientists – and others, including President Obama – who believes that man is responsible for the change in our planet. In a recent NASA survey, the space agency polled scientists on the question. The results were overwhelming; “Ninety-seven percent of climate scientists agree that climate-warming trends over the past century are very likely due to human activities,” the survey concluded.

Among those participating in the NASA study were the American Meteorological Society, the American Medical Association and the American Association for the Advancement of Science.

But if the earth’s temperature is changing, getting warmer, what are the reasons? “It’s really driven by the extra heat being absorbed that would otherwise go to space,” says Tans. The heat to which the lanky, Dutch-born researcher refers is not a sudden thing. The warming began with the launch of the Industrial Revolution and the astronomical appetite for coal and other fossil fuels that power economic growth.

Before the Industrial Revolution, coal was a local industry serving only those with quick and easy access to it. But from 1700 to 1750 production jumped by fifty percent. By 1850, coal production had increased 500 percent and its fingerprint was obvious. Smog and soot from the coal burning that fueled the age were dramatic and also held responsible for more than 700 deaths in London in one seven-day period in 1873. Pollution in some cities in China and India today nearly mirror 19th century London.

But coal, which produces carbon dioxide, is not the only culprit in this growing concern. Water vapor, methane and nitrous oxide, all greenhouse gases, are damaging to the planet in their own way. And, without serious exploration on a remedy, some scientists predict greenhouse gases that trap heat in the atmosphere could double during this century.

While energy portfolios have expanded to include clean energy, especially wind and solar, it remains carbon-based fuels like coal, oil and natural gas that are responsible for the majority of carbon dioxide in the air. The more of these gases in the atmosphere, the warmer the earth. And that, says Tans, impacts the entire ecosystem.

“Some plants respond more effectively, more strongly to carbon dioxide than others,” says Tans. But that also results in a change of “competitive relationships,” a change in eco-systems, especially in forests. But that’s only part of this equation. Another variable is the dramatic reduction in the world’s forests, many of which have disappeared, harvested for timber or, otherwise, converted to land for grazing cattle.

Interestingly, cattle, along with sheep, goats and a number of other animals, play a key role in the whole global warming conundrum. Each cow, with an average weight of 1,300 pounds, produces a lot of methane. In fact, a 2006 United Nations report claims livestock – especially cattle – “generates more greenhouse gas emissions as measured in CO2 equivalent – 18 percent – than transport (motor vehicles).” Methane, the report says, “is twenty-one percent more potent at trapping heat from the sun than carbon dioxide.”

But with a world population of seven billion and growing, and emerging economies like China and India demanding more and more resources, the day of reckoning may be coming – or already be here.

Scientists say eleven of the twelve warmest years since 1850 occurred between 1996 and 2006. Mountain glaciers and snow cover have also shown decreases in both northern and southern hemispheres. Many scientists also link conditions including California’s historic drought, the Midwest’s earlier and deadlier tornadoes and changes in the Jet Stream and the ocean’s Gulf Stream to the planet’s warming.Between 1961 and 1993, sea levels rose an average of 1.8 mm per year. Since then they’ve risen by 3.1 mm per year. Over a period of time, rising sea levels could negatively impact cities from Naples, Italy, to Naples, Florida.

“Sea level rise is our reality,” Miami Mayor Philip Levine said in a 2013 New York Times interview. “We are past the point of debating the existence of climate change.” The city is spending $400 million to upgrade its drainage system.

Seawater that had previously not been a concern could conceivably make it farther inland causing erosion, upsetting wetlands, compromising aquifers and upsetting a natural balance for fish, bird and plant habitat. Also, when more powerful storms reach land, more destruction could result.

Acting on global warming has been at a stalemate in Congress and pretty much followed party lines. But a handful of Senate Republicans voted earlier this year in favor of an amendment stating that humans do contribute to climate change. Colorado’s Republican freshman Senator Cory Gardner, despite campaigning as a new kind of Republican, was not among them. Several attempts by La Voz Bilingüe to reach Gardner for comment were unsuccessful.

Democratic Congressman Ed Perlmutter, who represents the state’s Seventh Congressional District which includes parts of Jefferson and Adams County and sits on the House Committee on Science, Space and Technology, however believes Congress needs to act quickly on a matter he calls one of America’s great challenges.

“Climate change is real,” says Perlmutter. “Congress must act to reduce greenhouse emissions, promote clean domestic energy production and provide key environmental protections in our communities.” Perlmutter favors extending the Wind Production Tax Credit which he believes will lessen America’s carbon footprint and “secure America’s energy independence.” Perlmutter has plenty of support in the scientific community.

“We, as a world, have to decide that we’re going to cut our CO2 production and our CO2 emissions,” says Dr. Karen Rosenlof, NOAA climate scientist. It may be a huge challenge, “but I wouldn’t say things are hopeless.”

For doubters that NOAA research on climate change/global warming is real, Rosenlof says all you need do is take a quick trip an hour or so west of Denver to the area around Keystone where the pine beetle has voraciously attacked and deforested thousands of acres of lodge pole pines.

“One of the things you can see in Colorado is the impact of these changes in temperature,” she says. And it’s not just the miles and miles of dead trees that have mounted up over the last several years. “That happens all the time,” says Rosenlof. Beetles and what they do to timber, says the Pennsylvania expat, are part of nature. “Our winters are not getting cold enough to kill them off. That’s climate change impact.”